WO2004114409A1 - 磁気ランダムアクセスメモリ - Google Patents
磁気ランダムアクセスメモリ Download PDFInfo
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- WO2004114409A1 WO2004114409A1 PCT/JP2004/008462 JP2004008462W WO2004114409A1 WO 2004114409 A1 WO2004114409 A1 WO 2004114409A1 JP 2004008462 W JP2004008462 W JP 2004008462W WO 2004114409 A1 WO2004114409 A1 WO 2004114409A1
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- WIPO (PCT)
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- magnetic
- wiring
- yoke layer
- magnetoresistive element
- layer
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
Definitions
- the present invention relates to a magnetic random access memory (hereinafter, referred to as “MRAM”).
- MRAM magnetic random access memory
- the present invention particularly relates to an MRAM in which a write current flows through a wiring provided with a yoke.
- MRAM is a powerful non-volatile memory capable of high-speed writing and having a large number of rewrites.
- a typical MRAM includes a memory cell array in which a plurality of magnetoresistive elements functioning as memory cells are arranged in a matrix.
- the magnetoresistive element includes a fixed ferromagnetic layer having a fixed spontaneous magnetization, a free ferromagnetic layer having a reversible spontaneous magnetization (hereinafter simply referred to as “magnetization”), a fixed ferromagnetic layer and a free ferromagnetic layer. And a spacer layer interposed between the layers.
- the free ferromagnetic layer is formed such that its magnetization direction can be either parallel or anti-parallel to the magnetization direction of the fixed ferromagnetic layer.
- the magnetoresistive element stores 1-bit data as a relative direction of magnetization between the fixed ferromagnetic layer and the free ferromagnetic layer.
- the magnetoresistive element takes two states, a "parallel” state in which the magnetization of the fixed ferromagnetic layer and the magnetization of the free ferromagnetic layer are parallel, and a "antiparallel” state in which the magnetizations are antiparallel. obtain.
- One of the “parallel” state and the “anti-parallel” state is associated with “0” and the other is associated with “:!”, And the magnetoresistive element can store 1-bit data.
- a magnetic field is generated by applying a write current to a wiring provided in the vicinity of the magnetoresistive element, and the magnetic field directs the magnetization of the free ferromagnetic layer in a desired direction. Done by The direction of the current is selected according to the direction of magnetization of the free ferromagnetic layer to be directed.
- a yoke that effectively reduces a write current can be a source of an unwanted bias magnetic field due to its shape anisotropy.
- the bias magnetic field is a magnetic field applied to the magnetoresistive element in a state where no write current is flowing.
- FIGS. 35A and 35B show a typical MRAM structure.
- a wiring 101 through which a write current flows is provided so as to extend in the X-axis direction, and a wiring 102 is provided so as to extend in the force axis direction.
- a magnetoresistive element 103 is provided at a position where the wiring 101 and the wiring 102 intersect.
- the yoke 104 is formed so as to cover the upper surface and the side surface of the wiring 101, and to align its end with the end of the wiring 101.
- the yoke 104 has a shape corresponding to the shape of the wiring 101, and is therefore formed in a shape that is long in the direction in which the wiring 101 extends.
- the shape anisotropy of the yoke 102 facilitates the magnetization of the yoke 104 in the direction in which the wiring 101 extends. As the width of the wiring 101 becomes smaller, the shape anisotropy of the yoke 104 becomes stronger, and the magnetization of the yoke 104 is more likely to be directed in the direction in which the wiring 101 extends.
- the magnetizing force of the yoke 104 The magnetic pole is generated at the end 104a in the X-axis direction of the yoke 104 by facing the direction in which the wiring 101 extends. This magnetic pole generates a bias magnetic field in the direction in which the wiring 101 extends. It is assumed that the length of the wiring 101 is 100 ⁇ m, the width is 1 ⁇ m, the thickness is 0.3 ⁇ m, the thickness of the yoke 104 is 50 nm, and the wiring 101 is made of NiFe.
- the bias magnetic field radiated from the end 104a has a distance of 10 xm from the end of the wiring 101 in the X-axis direction and a distance of 0.m from the bottom of the wiring 101. At the position of m, it has a strength of about 10 ( ⁇ e) in the X-axis direction.
- the bias magnetic field generated by the yoke has various effects on the operation of the MRAM. First, since the strength of the bias magnetic field generated by the yoke differs depending on the position in the memory cell array, the bias magnetic field causes variations in the characteristics of the magnetoresistive element. This Reduces the margin of the write current, which is not preferable.
- the bias magnetic field generated by the yoke is free from the free ferromagnetic layer of the magnetoresistive element. To reduce the coercive magnetic field, and to easily cause magnetization reversal due to thermal disturbance. The generation of a bias magnetic field by the yoke lowers the reliability of MRAM data retention, which is undesirable.
- JP-A-2002-299574, JP-A-2002-280526, and JP-A-2001-273759 disclose the structure of an MRAM for avoiding magnetic crosstalk. However, the disclosed structure does not address the generation of a bias magnetic field by the yoke.
- Patent Document 1 JP 2002-110938 A
- Patent Document 2 U.S. Patent Publication No. 6, 211, 090
- Patent Document 3 Japanese Patent Publication No. 2002-522915
- Patent Document 4 JP-A-9-1204770
- Patent Document 5 JP-A-2002-299574
- Patent Document 6 JP-A-2002-280526
- Patent Document 7 JP 2001-273759 A
- An object of the present invention is to suppress the influence of a bias magnetic field generated due to magnetic anisotropy of a yoke provided on a wiring for concentrating a magnetic field on a magnetoresistive element on an operation of an MRAM. It is to provide the technology of.
- Another object of the present invention is to provide a technique for applying a bias magnetic field generated by a yoke provided on a wiring for concentrating a magnetic field to the magnetoresistive element to the magnetoresistive element.
- an MRAM includes a plurality of magnetoresistive elements having magnetic anisotropy in a first direction, a plurality of magnetoresistive elements extending in a second direction different from the first direction, and A wiring through which a write current for writing data to the wiring is supplied; and a yoke layer covering at least a part of the surface of the wiring.
- the yoke layer is formed of a ferromagnetic material, and It extends in the direction.
- the plurality of magneto-resistive elements include a first magneto-resistive element and a second magneto-resistive element whose distance from an end of the yoke layer in the second direction is farther than the first magneto-resistive element.
- the magnetic anisotropy of the first magnetoresistance element near the end of the yoke layer is stronger than the magnetic anisotropy of the second magnetoresistance element far from the yoke layer.
- the fact that the first magnetoresistive element near the end of the yoke layer has a stronger magnetic anisotropy means that the yoke layer compensates for the decrease in the coercive magnetic field due to the bias magnetic field generated in the second direction, and the first magnetoresistive It effectively prevents the reversal of the element's magnetization.
- Adjustment of the magnetic anisotropy can be achieved by, for example, the shape of the first magnetoresistive element.
- the first magnetoresistive element and the first magnetoresistive element are the ratio of the length of the first magnetoresistive element in the first direction to the width of the first magnetoresistive element in the second direction.
- the aspect ratio may be designed to be greater than a second aspect ratio, which is a ratio of a length of the second magnetoresistive element in the first direction to a width of the second magnetoresistive element in the second direction.
- an MRAM in another aspect, includes a magnetoresistance element, a first wiring through which a write current for writing data to the magnetoresistance element flows, and at least a part of a surface of the first wiring.
- the first yoke layer is formed of a ferromagnetic material and extends in a first direction in which the first wiring extends.
- the magnetic field control structure for guiding the bias magnetic field generated by the first yoke layer so as to deviate from the magnetoresistive element effectively reduces the bias magnetic field linked to the magnetoresistive element. Therefore, the magnetic field control structure can suppress the influence of the bias magnetic field generated by the first yoke layer on the characteristics of the magnetoresistive element.
- the magnetic field control structure includes a magnetic shielding structure located between an end of the first yoke layer and the magnetoresistive element. It is preferable that the magnetic shielding structure obliquely intersects the first wiring. The obliquely intersecting magnetic shielding structure induces a large amount of bias magnetic field therein, and effectively reduces the bias magnetic field linked to the magnetoresistive element.
- the magnetic field shielding structure has a common laminated structure with at least a part of the magnetoresistive element.
- the MARM is not used for writing data to all the magneto-resistance elements included in the MRAM, extends in a second direction different from the first direction, and has an end of the first yoke layer.
- the second yoke layer functions as the magnetic shielding structure.
- the second wiring and the second yoke layer can be formed in the same step as the wiring and the yoke layer described above, and such a structure effectively simplifies the manufacturing process of the MRAM.
- the magnetic field control structure includes a magnetic layer covering the spacer layer, and the magnetic layer includes a yoke layer.
- a magnetic field emitted from one of the ends of the layer is directed to the other of the ends of the yoke layer.
- the magnetizations of the yoke layer and the magnetic layer are oriented in opposite directions.
- the spacer layer is formed such that the yoke layer and the magnetic layer are antiferromagnetically coupled, and more preferably, are coupled by antiferromagnetic exchange coupling. Is preferred.
- the MRAM further includes a second wiring extending in the first direction, and a ferromagnetic material, the MRAM extending in the first direction, and at least a part of a surface of the second wiring.
- the magnetic field control structure preferably includes a magnetic member that magnetically couples the first yoke layer and the second yoke layer.
- the magnetic member connects one end of the first yoke layer and one end of the second yoke layer. It is preferable to include a first magnetic member that magnetically couples, and a second magnetic member that magnetically couples the other end of the first yoke layer and the other end of the second yoke layer. .
- the first yoke layer, the second yoke layer, the first magnetic member, and the second magnetic member form a closed magnetic path to circulate a bias magnetic field, and the first yoke layer and the second yoke layer.
- the bias magnetic field emitted from the end in the first direction by the yoke layer is effectively prevented from interlinking the magnetoresistive element.
- the first wiring and the second wiring should not be construed as being limited to one. It must be interpreted that the yoke layer covering the three or more wirings can be magnetically coupled to the first magnetic member and the second magnetic member.
- the MRAM further includes a third magnetic member interposed between the first magnetic member and the second magnetic member, and the third magnetic member with respect to the magnetoresistive element. And a fourth magnetic member interposed between the first magnetic member and the second magnetic member.
- the third magnetic member and the fourth magnetic member promote circulation of the bias magnetic field generated by the first yoke layer and the second yoke layer, and effectively prevent the bias magnetic field from interlinking with the magnetoresistive element. I do.
- Such a configuration is also applicable when the second wiring is adjacent to the first wiring in the first direction.
- the MRAM further extends in the first direction, is formed of a ferromagnetic material, and a second wiring adjacent to the first wiring in the first direction, extends in the first direction, and A second yoke layer covering at least a part of the surface of the second wiring, the second yoke layer is close to the first yoke layer to such an extent as to be magnetically coupled to the first yoke layer.
- an MRAM according to the present invention is formed of a magnetoresistive element, a wiring through which a write current for writing data to the magnetoresistive element flows, and a ferromagnetic material, and the wiring extends A yoke layer extending in the direction, and covering at least a part of the surface of the wiring. The ends of the yoke layer are sufficiently separated so that the magnetic field radiated from the ends does not substantially affect the characteristics of the magnetoresistive element.
- the end of the yoke layer has a magnetic pole generated at the end of the yoke layer. It is preferable that the magnetic field to be linked is located away from the closest magnetoresistive element to such an extent that the magnetic field to be linked is one fifth or less of the intrinsic coercive field of the free ferromagnetic layer of the magnetoresistive element.
- the intrinsic coercive field of the free ferromagnetic layer means the coercive field of the free ferromagnetic layer when no magnetic field is applied in a direction perpendicular to the direction of the magnetic anisotropy of the free ferromagnetic layer.
- the distance of the closest magnetoresistive element from the end of the yoke layer causes the end of the yoke layer to be formed.
- the magnetic field that causes the magnetic pole to be linked to the magnetoresistive element is reduced.
- the MRAM comprises: a plurality of first wires extending in a first direction; a plurality of second wires extending in a second direction different from the first direction; A first yoke layer covering at least a part of each of the first wirings, and a magnetoresistive element arranged at each of intersections where the first and second wirings intersect are provided.
- the first end of the first yoke layer in the first direction is closest to the first end so that the distance from the closest magnetoresistive element closest to the first end to the first end is greater than or equal to the minimum pitch of the second wiring. It is located away from the magnetoresistive element. The distance of the closest magnetoresistive element from the end of the first
- the magnetic field that causes the magnetic pole generated at the end of the first yoke layer to interlink with the magnetoresistive element is reduced.
- a second end of the second yoke layer in the second direction is closest to the first end.
- the distance from the magnetoresistive element to the first end is located at a distance from the closest magnetoresistive element so that the distance is equal to or greater than the minimum pitch of the first wiring. Since the distance of the closest magnetoresistive element from the end of the second yoke layer is reduced, the magnetic field generated by the magnetic pole generated at the end of the second yoke layer interlinks with the magnetoresistive element.
- the present invention provides a technique for suppressing the influence of a bias magnetic field generated by a yoke provided on a wiring for concentrating a magnetic field on a magnetoresistive element on the operation of an MRAM. Can be provided.
- FIG. 1 is a top view showing a first embodiment of an MRAM according to the present invention.
- FIG. 2 is a cross-sectional view showing a first embodiment of the MRAM according to the present invention.
- FIG. 3 is a sectional view showing a first embodiment of an MRAM according to the present invention.
- FIG. 4 is a top view showing a second embodiment of the MRAM according to the present invention.
- FIG. 5 is a sectional view showing a second embodiment of the MRAM according to the present invention.
- FIG. 6 is a sectional view showing a second embodiment of the MRAM according to the present invention.
- FIG. 7 is a view showing an operation of the magnetic shielding structure 26.
- FIG. 8 is a cross-sectional view showing a modification of the MRAM according to the second embodiment.
- FIG. 9 is a plan view showing a modification of the MRAM according to the second embodiment.
- FIG. 10 is a cross-sectional view showing another modification of the MRAM according to the second embodiment.
- FIG. 11 is a plan view showing another modification of the MRAM according to the second embodiment.
- FIG. 12 is a sectional view showing still another modification of the MRAM according to the second embodiment.
- Garden 13 is a sectional view showing still another modification of the MRAM according to the second embodiment.
- FIG. 14 is a plan view showing still another modified example of the MRAM according to the second embodiment.
- FIG. 15 is a sectional view showing still another modification of the MRAM according to the second embodiment.
- FIG. 16 is a cross-sectional view showing still another modified example of the MRAM according to the second embodiment.
- Garden 17 is a sectional view showing a third embodiment of the MRAM according to the present invention.
- FIG. 18 is a sectional view showing a third embodiment of the MRAM according to the present invention.
- Garden 19 is a sectional view showing a modification of the third embodiment of the MRAM according to the present invention.
- FIG. 20 is a plan view showing a fourth embodiment of the MRAM according to the present invention.
- FIG. 21 is a sectional view showing a fourth embodiment of the MRAM according to the present invention.
- FIG. 22 is a sectional view showing a fourth embodiment of the MRAM according to the present invention.
- FIG. 23 is a sectional view showing a modification of the fourth embodiment of the MRAM according to the present invention.
- FIG. 24 is a sectional view showing another modification of the fourth embodiment of the MRAM according to the present invention.
- FIG. 25 is a plan view showing another modified example of the fourth embodiment of the MRAM according to the present invention.
- FIG. 26 is a sectional view showing still another modification of the fourth embodiment of the MRAM according to the present invention.
- FIG. 27 is a cross-sectional view showing yet another modification of the fourth embodiment of the MRAM according to the present invention.
- FIG. 28 is a plan view showing still another modified example of the fourth embodiment of the MRAM according to the present invention.
- FIG. 29 is a plan view showing still another modification of the fourth embodiment of the MRAM according to the present invention.
- FIG. 30 is a plan view showing an MRAM according to a fifth embodiment of the present invention.
- FIG. 31 is a sectional view showing an MRAM according to a fifth embodiment.
- FIG. 32 is a cross-sectional view showing a modification of the MRAM of the fifth embodiment.
- FIG. 33 is a plan view showing a modification of the MRAM of the fifth embodiment.
- FIG. 34 is a plan view showing an MRAM according to a sixth embodiment of the present invention.
- FIG. 35A is a cross-sectional view showing a conventional MRAM.
- FIG. 35B is a cross-sectional view showing a conventional MRAM.
- the upper write wiring 11 is provided so as to extend in the X-axis direction
- the lower write wiring 12 extends in the y-axis direction perpendicular to the X-axis direction. It is provided as follows.
- a magnetoresistive element 13 is provided at each of the intersections of the upper write wiring 11 and the lower write wiring 12. As shown in FIG. 2, the magnetoresistive element 13 includes a free ferromagnetic layer 13a, a fixed ferromagnetic layer 13b, and a spacer layer 13c interposed therebetween. .
- the free ferromagnetic layer 13a is electrically connected to the overwriting wiring 11 via the metal cap layer 16.
- the fixed ferromagnetic layer 13b is formed on the lower write wiring 12, and is electrically connected to the lower write wiring 12.
- Each of the magnetoresistive elements 13 holds 1-bit data as the direction of magnetization of the free ferromagnetic layer 13a.
- the magnetoresistive element 13 is formed in a shape elongated in the y-axis direction, and the magnetic anisotropy of the magnetoresistive element 13 is oriented parallel to the y-axis direction.
- the upper write wiring 11 has an upper surface and side surfaces of a conductor covered with a yoke layer 14, and as shown in FIG. The sides are covered by a yoke layer 15.
- Each of the yoke layers 14 and 15 is formed of a magnetically soft ferromagnetic material.
- the yoke layer 14 is formed so as to be aligned with the ends lla and lib of the write wiring 11 on the ends 14a and 14b in the X-axis direction.
- the yoke layer 15 is Are formed so as to be aligned with the ends 12a and 12b of the lower write wiring 12, respectively. Therefore, the yoke layer 14 has a shape elongated in the X-axis direction, and the yoke layer 15 has a shape elongated in the y-axis direction.
- the yoke layer 14 generates a bias magnetic field Hx in the X-axis direction due to its shape anisotropy. Due to the shape anisotropy of the yoke layer long in the X-axis direction, the magnetization of the yoke layer 14 is directed in the X-axis direction. Due to this magnetization, magnetic poles are generated at the ends 14a and 14b of the yoke layer 14, and the magnetic poles generate a bias magnetic field in the X-axis direction.
- the magnetic field radiated in the axial direction is resistant to thermal disturbance of data stored in magnetoresistive element 13 near ends 14 a and 14 b of yoke layer 14. Weaken.
- the strength of the bias magnetic field Hx applied to each of the magnetoresistive elements 13 in the X-axis direction increases as the distance from the ends 14a and 14b of the yoke layer 14 decreases.
- the coercive magnetic field (reversal magnetic field) of a certain magnetic resistance element 13 decreases as the bias magnetic field Hx force S strong level applied to the magnetic resistance element 13 increases. Therefore, the closer the ends 14a and 14b of the yoke layer 14 are, the weaker the coercive magnetic field of the magnetoresistive element 13 is, and accordingly, the resistance of the magnetoresistive element 13 to thermal disturbance is reduced.
- the magnetoresistive element 13 close to the ends 14a and 14b of the yoke layer 14 (ie, The magnetoresistive element 13) near the ends l la and l ib of the wiring 11 has stronger magnetic anisotropy than the magnetoresistive element 13 far from the ends 14a and 14b.
- the magnetic anisotropy of a given magnetoresistive element 13 is determined by the reciprocal of the distance from the end closer to the magnetoresistive element 13 among the two ends 14a and 14b of the yoke layer 14. It is set to increase monotonically in a broad sense.
- the resistance element 13 is formed longer and narrower in the y-axis direction than the magnetoresistance element 13 far from the ends 14a and 14b of the yoke layer 14. That is, using the width w in the y-axis direction and the length L in the X-axis direction of the magnetoresistive element 13,
- the aspect ratio R of the magnetoresistive element 13 is calculated by the following equation:
- Each of the magnetoresistive elements 13 has an aspect ratio R of the magnetoresistive element 13 with respect to a reciprocal of a distance d of the magnetoresistive element 13 from a near end of the ends 14a and 14b of the yoke layer 14. It is formed in a shape that monotonically increases in a broad sense. In FIG. 1, the magnetoresistive element 13 closest to the ends 14a and 14b of the yoke layer 14 is formed in a shape such that its aspect ratio R is larger than the aspect ratio R of the other magnetic resistance elements 13. .
- the area of the magnetoresistive element 13 (that is, the area of the surface where the spacer layer 13c is joined to the free ferromagnetic layer 13a) is The magneto-resistive element 13 is also substantially the same.
- Such a shape of the magnetoresistive element 13 compensates for a decrease in resistance to thermal disturbance caused by a bias magnetic field generated in the X-axis direction by the yoke layer 14.
- a plurality of upper write wirings 21 extend in the X-axis direction
- a plurality of lower write wirings 22 extend in the X-axis direction
- the magnetoresistive element 23 is arranged at each of the intersections of the upper write wiring 21 and the lower write wiring 22.
- the magneto-resistive elements 23 are arranged in a matrix to form a memory cell array.
- the magnetoresistive element 23 includes a free ferromagnetic layer (not shown), a fixed ferromagnetic layer (not shown), and a spacer layer (not shown) interposed therebetween.
- Each of the magnetoresistive elements 23 stores 1-bit data as the direction of magnetization of the free ferromagnetic layer.
- the upper surface and the side surface of the upper write wiring 21 are covered with a yoke layer 24 formed of a ferromagnetic material.
- the ends 24a and 24b of the yoke layer 24 are aligned with the ends 21a and 21b of the upper write wiring 21, respectively.
- the shape of the yoke layer 24, which is long in the x-axis direction, causes the magnetization of the yoke layer 24 to be oriented in the X-axis direction, and generates a bias magnetic field in the yoke layer 24 in the X-axis direction.
- the bottom and side surfaces of the lower write wiring 22 are covered with a yoke layer 25 formed of a ferromagnetic material.
- the ends 25a and 25b of the yoke layer 25 are aligned with the ends 22a and 22b of the lower writing line 22.
- the shape of the yoke layer 25 that is long in the y-axis direction causes the magnetization of the yoke layer 25 to be directed in the y-axis direction, and generates a bias magnetic field in the yoke layer 25 in the y-axis direction.
- the magnetic shielding structure 26 including the magnetic film is formed so as to surround the memory cell array composed of the magnetoresistive elements 23 in a plane parallel to the xy plane. It is formed. As shown in FIG. 5, the magnetic shielding structure 26 is formed below the upper write wiring 21 and above the lower write wiring 22. As shown in FIG. 6, the magnetic shield structure 26 passes between the ends 21a and 21b of the upper write wiring 21 (that is, the ends 24a and 24b of the yoke layer 24) and the array of the magnetoresistive elements 23. are doing. Further, the magnetic shielding structure 26 passes between the ends 22a and 22b of the lower write wiring 22 and the array of the magnetoresistive elements 23 as shown in FIG.
- the magnetic shielding structure 26 having such a structure induces a bias magnetic field generated by the yoke layer 24 and the yoke layer 25 therein, and prevents the bias magnetic field from interlinking with the magnetoresistive element 23. To this effect, the magnetic shielding structure 26 effectively reduces the bias magnetic field applied to the magnetoresistive element 23.
- the magnetic shielding structure 26 is connected to the ends 21 a and 21 b of the upper write wiring 21 and the ends 22 a and 22 b of the lower write wiring 22. It is preferable that the upper write wiring 21 and the lower write wiring 22 are formed so as to be convex and obliquely intersect with the upper write wiring 21 and the lower write wiring 22.
- Such a structure of the magnetic shielding structure 26 allows the bias magnetic field generated by the yoke layers 24 and 25 to pass more inside the magnetic shielding structure 26, and the bias magnetic field applied to the magnetoresistive element 23. It is effective in reducing
- the bias magnetic field H is applied to the portions 26a and 26b in the direction of the force.
- the portions 26a and 26b are plate members arranged in a V shape so as to protrude toward the upstream side of the bias magnetic field H, and the portions 26a and 26b are NiFe having a width of 1 zm and a thickness of 50 nm. It is formed with. 3 m away from parts 26a, 26b downstream of bias field H.
- the magnitude of the magnetic field at the position is less than one third of the magnetic field without the magnetic shielding structure 26.
- the magnitude of the magnetic field at a distance of 5 / im from the portions 26a and 26b is about 60% of the magnetic field without the magnetic shielding structure 26.
- the magnetic shielding structure 26 has the same laminated structure as at least a part of the magnetoresistive element 23 in that the manufacturing process of the MRAM can be simplified. is there.
- the magnetic shield structure 26 can be formed in the same laminated structure as the fixed ferromagnetic layer of the magnetoresistive element 23 including the fixed ferromagnetic layer, the free ferromagnetic layer, and the spacer layer.
- the magnetic shielding structure 26 can be formed in the same laminated structure as the fixed ferromagnetic layer, the free ferromagnetic layer, and the spacer layer.
- the magnetic shielding structure 26 can be arranged to be joined to the upper surface of the lower write wiring 22.
- Such a structure is obtained when the magnetic shield structure 26 is formed in the same laminated structure as at least a part of the magnetoresistive element 23, and the magnetic resistance element 23 is formed by bonding to the upper surface of the lower write wiring 22. It is suitable for.
- the magnetic shield structure 26 is arranged so as to be joined to the upper surface of the lower write wiring 22, as shown in FIG. 9, the magnetic shield structure 26 has slits 26 c located between the lower write wiring 22. Is formed. Due to the slit 26c, insulation between the adjacent lower write wirings 22 is maintained. The width of the slit 26c is selected to be as small as possible in a range where the insulation between the lower write wirings 22 is maintained.
- the magnetic shielding structure 26 can be arranged to be joined to the lower surface of the upper write wiring 21.
- Such a structure is used when the magnetic shield structure 26 has the same laminated structure as at least a part of the magnetoresistive element 23 and the magnetoresistive element 23 is formed by bonding to the lower surface of the overwrite wiring 21. It is suitable.
- the slit 26 d located between the upper write wiring 21 is formed in the magnetic shielding structure 26. Is provided.
- the slit 26d maintains insulation between the adjacent upper write wirings 21.
- the width of the slit 26d is selected as small as possible in a range where the insulation between the upper write wirings 21 is maintained.
- a magnetic shielding wiring 27 covered with a yoke layer 28 and a yoke layer 28 are provided instead of the magnetic shielding structure 26, a magnetic shielding wiring 27 covered with a yoke layer 28 and a yoke layer 28 are provided. layer A magnetic shielding wire 29 covered with 30 can be formed. As shown in FIG. 14, the magnetic shielding wiring 27 and the yoke layer 28 extend in the X-axis direction, and the magnetic shielding wiring 29 and the yoke layer 30 extend in the y-axis direction. The magnetic shielding wires 27 and 29 are not used for writing data to the magnetoresistive element 23. As shown in FIG.
- the magnetic shield wiring 27 and the yoke layer 28 have the same structure as the upper write wiring 21 and the yoke layer 24, and are connected to the ends 22a and 22b of the lower write wiring 22. It is provided between the upper write wiring 21 and the array.
- the magnetic shielding wiring 29 and the yoke layer 30 have the same structure as the lower write wiring 22 and the yoke layer 25, and are connected to the ends 21a and 21b of the upper write wiring 21. It is provided between the lower write wiring 22 and the array.
- the yoke layers 28 provided on the side surfaces and the upper surface of the magnetic shielding wiring 27 effectively guide the bias magnetic field generated in the y-axis direction by the yoke layers 25 and link them to the magnetoresistive element 23. Prevention.
- the yoke layer 20 provided on the side and top surfaces of the magnetic shielding wiring 29 guides a bias magnetic field generated in the X-axis direction by the yoke layer 24 into the yoke layer 20 and interlinks with the magnetic resistance element 23. Effectively prevent
- a magnetic shielding wiring 27 covered with a yoke layer 28 is formed in addition to the magnetic shielding structure 26 .
- a magnetic shielding wire 29 covered with a yoke layer 30 can be formed in addition to the magnetic shielding structure 26 and the yoke layer 28 .
- the use of the magnetic shielding structure 26 and the yoke layer 28 more effectively prevents the bias magnetic field generated in the y-axis direction by the yoke layer 25 from interlinking with the magnetoresistive element 23.
- the use of the magnetic shielding structure 26 and the yoke layer 30 more effectively prevents the bias magnetic field generated in the X-axis direction by the yoke layer 24 from interlinking with the magnetoresistive element 23.
- FIGS. 17 and 18 show an MRAM according to the third embodiment of the present invention.
- the magnetic field generated by the magnetic pole generated at one end of the yoke layer is induced at the other end of the yoke layer, thereby reducing the bias magnetic field applied to the magnetoresistive element.
- an upper write wiring 41 whose side surface and upper surface are covered with a yoke layer 42, extend in the force axis direction, and are shown in FIG.
- a lower write wiring 43 whose side surface and lower surface are covered with a yoke layer 44 extends in the y-axis direction.
- the yoke layers 42 and 44 are formed of a conductive ferromagnetic material such as NiFe.
- a magnetoresistive element 45 is provided at each position where the upper write wiring 41 and the lower write wiring 42 intersect.
- the side and top surfaces of the yoke layer 42 covering the upper write wiring 41 are covered with a spacer layer 47, and the side and top surfaces of the spacer layer 47 are It is covered with a magnetic layer 48 made of a ferromagnetic material.
- the two ends of the magnetic layer 48 in the X-axis direction are aligned with the two ends of the yoke layer 42, respectively.
- the shape of the yoke layer 42 and the magnetic layer 48 covering the upper write wiring 41 extending in the X-axis direction is long in the X-axis direction. Therefore, the magnetizations of the yoke layer 42 and the magnetic layer 48 are oriented in the X-axis direction due to the shape anisotropy.
- the magnetization oriented in the X-axis direction generates a magnetic pole at the end of the yoke layer 42 and the magnetic layer 48 in the X-axis direction.
- the magnetization of yoke layer 42 is different from the magnetization of magnetic layer 48. Can be turned in the opposite direction. This is because most of the magnetic field generated by the magnetic pole at one end of the yoke layer 42 is circulated to the other end of the yoke layer 42 through the magnetic material layer 48, and the bias magnetic field generated by the magnetic pole generated at the end of the yoke layer 42 emits. Is effectively prevented from being applied to the magnetoresistive element 45.
- the yoke layer 42 is formed of a 50 nm NiFe film
- the magnetic layer 48 is formed of a 50 nm NiFe film
- the spacer layer 47 is formed of a 20 nm thick insulator.
- the intensity of the bias magnetic field applied to the magnetoresistive element 45 by the yoke layer 42 becomes 1/50 or less.
- the spacer layer 47 is formed so that the yoke layer 42 and the magnetic layer 48 are magnetically and ferromagnetically. Designed not to combine. If the spacer layer 47 is improperly designed, the yoke layer 42 and the magnetic layer 48 may be ferromagnetically coupled by exchange coupling. Ferromagnetic coupling between the yoke layer 42 and the magnetic layer 48 is not preferable because the magnetization of the yoke layer 42 is directed in the same direction as the magnetization of the magnetic layer 48.
- the spacer layer 47 is designed such that the yoke layer 42 and the magnetic layer 48 are antiferromagnetically coupled.
- the spacer layer 47 is preferably designed so that the yoke layer 42 and the magnetic layer 48 are magnetically coupled by antiferromagnetic exchange coupling.
- the spacer layer 47 can be formed of either an insulator or a conductor. However, in order to increase the magnetic field applied to the magnetoresistive element 45 by the write current flowing through the upper write wiring 41, the spacer layer 47 is preferably formed of an insulator. Since the spacer layer 47 is formed of an insulator, the effective thickness of the wiring through which the write current flows (i.e., the upper write wiring 41 and the yoke layer 42) is reduced and applied to the magnetoresistive element 45. The magnetic field increases.
- the yoke layer 42 and the magnetic layer 48 are designed so that their coercive fields are different. You. The difference in the coercive magnetic field between the yoke layer 42 and the magnetic layer 48 makes it possible to reverse the magnetizations of the yoke layer 42 and the magnetic layer 48 by applying an external magnetic field. For example, suppose that the coercive field of the yoke layer 42 is larger than the coercive field of the magnetic layer 48.
- the yoke layer 42 larger than the coercive magnetic field of the magnetic layer 48 is applied.
- a second magnetic field smaller than the coercive magnetic field is applied in a direction opposite to the first magnetic field, the magnetization of the yoke layer 42 and the magnetization of the magnetic layer 48 can be directed in the opposite direction.
- the yoke layer 44, the spacer layer 49, and the magnetic layer 50 are also configured similarly to the yoke layer 42, the spacer layer 47, and the magnetic layer 48. As shown in FIG. 18, the side and upper surfaces of the yoke layer 44 covering the lower write wiring 43 are covered with a spacer layer 49, and the side and upper surfaces of the spacer layer 49 are formed of a ferromagnetic material. Covered with the magnetic layer 50 formed by the above. Referring to FIG. 17, the two ends of magnetic layer 50 in the y-axis direction are aligned with the two ends of yoke layer 44, respectively.
- the shape of the yoke layer 44 and the magnetic layer 50 covering the upper write wiring 41 extending in the y-axis direction is long in the X-axis direction. Therefore, the magnetizations of the yoke layer 44 and the magnetic layer 50 are oriented in the y-axis direction due to shape anisotropy. The magnetization oriented in the y-axis direction generates a magnetic pole at the y-axis end of the yoke layer 44 and the magnetic layer 50.
- the magnetic field emitted from the magnetic pole at the end of yoke layer 44 is applied to magnetoresistive element 45.
- the magnetization of the yoke layer 44 is directed in the opposite direction to the magnetization of the magnetic layer 50 in order to prevent heat. This is because most of the magnetic field generated by the magnetic pole at one end of the yoke layer 44 is circulated through the magnetic layer 50 to the other end of the yoke layer 44, and the magnetic field generated at the end of the yoke layer 44 is generated by the magnetic resistance. It is effectively prevented from being applied to the element 45.
- the spacer layer 49 is formed such that the yoke layer 44 and the magnetic layer 50 are magnetically ferromagnetic.
- the yoke layer 44 and the magnetic layer 49 are designed to be antiferromagnetically coupled so as not to couple with each other.
- the spacer layer 49 can be formed of either an insulator or a conductor. However, in order to increase the magnetic field applied to the magnetoresistive element 45 when a write current flows through the lower write wiring 41, the spacer layer 49 is preferably formed of an insulator. You.
- the yoke layer 44 and the magnetic layer 50 are so arranged that their coercive magnetic fields are different. Designed.
- the difference in the coercive field between the yoke layer 55 and the magnetic layer 50 makes it possible to reverse the magnetizations of the yoke layer 44 and the magnetic layer 50 by applying an external magnetic field.
- the coercive field of the yoke layer 44 is larger than the coercive field of the magnetic layer 50
- the first magnetic field larger than the coercive field of both the yoke layer 44 and the magnetic layer 50 is parallel to the y-axis direction.
- a second magnetic field which is larger than the coercive field of the yoke layer 44 and is larger than the coercive field of the magnetic layer 50, is applied in a direction opposite to the first magnetic field, so that the magnetization of the yoke layer 44 becomes magnetic.
- the magnetization of the body layer 50 can be directed in the opposite direction.
- the magnetic layer 48 and the magnetic layer 50 are magnetically coupled to the yoke layer 42 and the yoke layer 44, respectively. Effectively applied.
- the spacer layer 47 when the spacer layer 47 is an insulator, the spacer layer 47 and the magnetic layer 48 are Instead of being provided corresponding to each of the above, it can be formed so as to cover all the upper write wirings 41 and the yoke layer 43.
- the structure shown in FIG. 19 is advantageous because the magnetic layer 48 'can be easily formed.
- the spacer layer 49 is an insulator, The spacer layer 49 and the magnetic layer 50 can be integrally formed instead of being provided corresponding to each of the lower write wirings 43.
- FIG. 20 shows a fourth embodiment of the MRAM according to the present invention.
- the magnetic field force radiated from the end of the yoke layer covering one write wiring is guided to the end of the yoke layer covering another write wiring, and the magnetic field does not link the magnetoresistive element. And so on. Thereby, the bias magnetic field applied to the magnetoresistive element is reduced.
- the upper write wiring 51 whose side and upper surfaces are covered with a yoke layer extends in the X-axis direction
- the lower write wiring 51 whose side and lower surfaces are covered with a yoke layer extends in the y-axis direction.
- the yoke layer is not shown in FIG. 20 for clarity.
- the yoke layer is formed of a conductive ferromagnetic material such as NiFe.
- a magnetoresistive element (not shown) is provided at each position where the upper write wiring 51 and the lower write wiring 52 intersect.
- Two upper write wirings 51 adjacent in the y-axis direction constitute a wiring set 53
- two lower write wirings 52 adjacent in the X-axis direction constitute a wiring set 54.
- a conductive magnetic film 55a is provided so as to overlap the first ends 51a of the two upper write wirings 51 included in one wiring set 53, and the conductive magnetic film 55b is The two upper write wirings 51 included in the one wiring set 53 are provided so as to overlap the second ends 51b of the upper write wirings 51.
- FIG. 21 is a cross-sectional view showing a structure near the first end 51a (and the second end 51b) of the upper write wiring 51. The top and side surfaces of the upper write wiring 51 are covered with a yoke layer 57.
- the first end 51a (and the second end 51b) of the upper write wiring 51a and the yoke layer 57 are covered with an insulating film 58, and the magnetic films 55a and 55b are provided on the insulating film 58.
- the insulating film 58 electrically insulates the two upper write wires 51.
- the end of the yoke layer 57 in the X-axis direction faces the magnetic films 55a and 55b with the insulating film 58 interposed therebetween.
- Such a structure magnetically couples the yoke layer 57 and the magnetic films 55a and 55b.
- the yoke layer 57 that covers the overwrite wiring 51 has a shape that is long in the X-axis direction, and the magnetization of the yoke layer 57 is oriented parallel to the X-axis direction due to shape anisotropy. Therefore, a magnetic pole is generated at the end of the yoke layer 57 in the X-axis direction.
- the end of the yoke layer 57 faces the magnetic films 55a and 55b. Therefore, the magnetic pole generated at the end of the yoke layer 57 is magnetically coupled to the magnetic films 55a and 55b.
- FIG. 22 is a cross-sectional view showing a structure near the first end 52a (and the second end 52b) of the lower write wiring 52.
- the lower write wiring 52 is embedded in a groove provided in the interlayer insulating film 59.
- the lower and side surfaces of the lower write wiring 52 are covered with a yoke layer 60. It should be noted that the end of the lower write wiring 52 in the y-axis direction is also covered by the yoke layer 60.
- the yoke layer 60 includes a lower surface covering portion 60a that is in contact with the lower surface of the underwriting wire 52, and an end portion 60b that covers the y-axis end of the underwriting wire 52.
- the lower write wiring 52, the interlayer insulating film 59, and the yoke layer 60 are covered with the insulating film 61.
- the magnetic films 56a and 56b are formed on the insulating film 61.
- the insulating film 61 electrically insulates the two lower write wirings 52.
- the upper end of the end portion 60b of the yoke layer 60 faces the magnetic film 56a (and 56b) with the insulating film 61 interposed therebetween.
- Such a structure magnetically couples the yoke layer 60 and the magnetic films 56a and 56b.
- the lower surface covering portion 60a of the yoke layer 60 that covers the underwriting wiring 52 has a long shape in the X-axis direction, and the magnetization of the lower surface covering portion 60a is in the X-axis direction due to the shape anisotropy. Turn parallel to. Furthermore, since the end portion 60b of the yoke layer 60 extends upward (z-axis direction), the magnetization of the end portion 60b is oriented in the z-axis direction. Therefore, a magnetic pole is generated at the upper end of the end portion 60b of the yoke layer 60.
- the magnetic field generated at the upper end of the end portion 60b of the yoke layer 60 is magnetically generated by the magnetic films 56a and 56b.
- the magnetizations of two yoke layers 57 covering upper write wiring 51 of one wiring set 53 are opposite to each other. This circulates the bias magnetic field generated by the yoke layer 57 and prevents the magnetic field from being linked to the magnetoresistive element. Since the yoke layer 57 is magnetically coupled to the magnetic films 55a and 55b, the two yokes included in one wiring set 53 Substantially all of the bias magnetic field generated by one of the layers 57 is guided to the other yoke layer 57 via the magnetic films 55a and 55b. This means that the yoke layer 57, the magnetic films 55a and 55b, the force S, and, in effect, constitute a closed magnetic circuit. Therefore, the bias magnetic field generated by the yoke layer 57 does not substantially link with the magnetoresistive element.
- the magnetizations of the two yoke layers 60 covering the lower write wiring 52 of one wiring set 54 are opposite to each other. This circulates the bias magnetic field generated by the yoke layer 60 to prevent the yoke layer 60 from interlinking with the magnetoresistive element. Since the yoke layer 60 is magnetically coupled to the magnetic films 55a and 55b, substantially all of the bias magnetic field generated by one of the two yoke layers 60 included in one wiring group 54 is It is guided to another shock layer 60 through the magnetic films 56a and 56b. This means that the yoke layer 60 and the magnetic films 56a and 56b substantially form a closed magnetic path. Therefore, the bias magnetic field generated by the yoke layer 60 does not substantially link with the magnetoresistive element.
- the magnetizations of the two yoke layers 57 covering the two upper write wirings 51 included in one wiring set 53 can be directed in opposite directions by the following steps. After the MRAM shown in FIG. 20 is formed, the MRAM is heat-treated at a temperature higher than the Curie point of the yoke layer 57. When the magnetizations of the two yoke layers 57 covering the upper write wiring 51 of one wiring set 53 are opposite, the potential energy of the magnetization is minimized. The magnetization of the two yoke layers 57 covering the write wiring 51 on the one wiring set 53 is spontaneously directed in the opposite direction.
- the magnetizations of the two yoke layers 60 covering the two lower write wirings 52 included in one wiring set 54 can also be directed in opposite directions.
- the bias magnetic fields generated by the yoke layers 57 and 60 covering the upper write wiring 51 and the lower write wiring 52 are confined in the closed magnetic path, and The bias magnetic field is prevented from interlinking with the magnetoresistive element.
- the structures near the ends of the upper write wiring 51 and the lower write wiring 52 can be variously changed.
- FIG. 23 shows a modification of the structure near the end of the upper write wiring 51.
- insulating magnetic films 55a 'and 55b are used instead of the conductive magnetic films 55a and 55b.
- insulating magnetic films 55a 'and 55b are used. 'Can be used.
- the insulating magnetic films 55a 'and 55b' can be formed directly in contact with the yoke layer 57.
- the direct contact of the insulating magnetic films 55a 'and 55b' with the yoke layer 57 strengthens the magnetic coupling between the insulating magnetic films 55a 'and 55b' and the yoke layer 57, and provides a more complete closed magnetic circuit. Allow formation.
- FIGS. 24 and 25 show modifications of the structure near the end of the lower write wiring 52.
- a groove facing the end portion 60b of the yoke layer 60 is formed in the interlayer insulating film 59, and the inner surface of the groove is covered with the insulating film 61.
- the magnetic films 56a and 56b are formed on the insulating film 61 so as to cover the inner surface of the groove.
- the magnetic films 56a and 56b are formed so as to have the concave portions 62.
- the magnetic films 56a and 56b and the end portion 60b of the yoke layer 60 face each other with a larger area, and the magnetic coupling between the magnetic films 56a and 56b and the yoke layer 60 is strengthened. This is preferred because it allows the formation of a more complete closed magnetic circuit.
- insulating magnetic films 56a ′ and 56b ′ may be used instead of conductive magnetic films 56a and 56b.
- the insulating magnetic films 56a 'and 56b' can be formed directly in contact with the yoke layer 60.
- the insulating magnetic films 56a ′ and 56b ′ can be covered with the insulating film 61.
- the insulating film 61 is formed so as not to cover the end portion 60a of the yoke layer 60, and the insulating magnetic films 56a 'and 56b' cover the end portion 60a of the yoke layer 60. And it can be formed so as to overlap the insulating film 61.
- the direct contact of the insulating magnetic films 56a 'and 56b' with the yoke layer 60 strengthens the magnetic coupling between the insulating magnetic films 56a 'and 56b' and the yoke layer 60, and provides more complete magnetic closure. Enables the formation of roads.
- the number of upper write wirings 51 included in one wiring set 53 and the number of lower write wirings 52 included in one wiring set 54 are not limited to two.
- one wiring set 53 can be composed of four upper write wirings 51
- one wiring set 54 can be composed of four lower write wirings 52. .
- the direction of magnetization of the yoke layer 57 is such that the yoke layer 57, the magnetic films 55a, and 55b close the closed magnetic path by the heat treatment. It can be directed to form.
- the MRAM is the Curie point of the yoke layer 57 After the heat treatment at a higher temperature, the temperature of the MRAM is returned to room temperature, so that the direction of magnetization of the yoke layer 57 is such that the yoke layer 57, the magnetic films 55a, and 55b form a closed magnetic path. Turn around.
- the magnetic film 55a is formed so as to overlap the first ends 51a of all the upper write wirings 51, and the magnetic film 55b is formed. It can be formed so as to overlap all the second ends 51b.
- the magnetic film 55a and the magnetic film 55b are connected by a pair of magnetic films 55c and 55d.
- the magnetic films 55c and 55d are located at positions facing each other across the array of the upper write wiring 51.
- the magnetic film 56a is formed so as to overlap the first ends 52a of all the lower write wirings 52
- the magnetic film 56b is formed so as to overlap the second ends 52b of all the lower write wirings 52. Can be formed to overlap.
- the magnetic films 56c and 56d are located at positions facing each other across the array of the lower write wiring 52. The strong structure promotes circulation of the bias magnetic field radiated from the end of the yoke layer 60 covering the lower write wiring 52, and more effectively prevents the bias magnetic field from interlinking with the magnetoresistive element.
- FIG. 30 shows a fifth embodiment of the MRAM according to the present invention.
- two blocks 71 and 72 are provided adjacent to each other in the X-axis direction.
- an upper write wiring 73 whose side and upper surfaces are covered by a yoke layer extends in the X-axis direction
- a lower write wiring 74 whose side and lower surfaces are covered by the yoke layer extends in the y-axis direction. Is established.
- a resistance element is provided at each of the positions where the upper write wiring 73 and the lower write wiring 74 intersect.
- an upper write wiring 75 whose side and upper surfaces are covered with a yoke layer extends in the X-axis direction
- a lower write wiring 76 whose side and lower surfaces are covered with a yoke layer has a y line. It extends in the axial direction.
- a magnetic resistance element is provided at each position where the upper write wiring 75 and the lower write wiring 76 intersect.
- a conductive magnetic film 77 is provided so as to overlap the end of the upper write wiring 73 on the block 71 and the end of the upper write wiring 75 on the block 72.
- FIG. 31 shows the structure near the ends of the upper write wirings 73 and 75.
- the upper write wirings 73 and 75 are covered by the yoke layers 78 and 79, respectively.
- the upper write wirings 73 and 75 and the yoke layers 78 and 79 are covered with an insulating film 80.
- the magnetic film 77 is formed on the insulating film 80.
- the insulating film 80 electrically insulates the upper write wirings 73 and 75.
- the magnetic film 77 faces the yoke layers 78 and 79 via the insulating film 80, and is magnetically coupled to the yoke layers 78 and 79.
- the magnetic film 77 includes a yoke layer 78 that covers the upper write wiring 73 of the block 71;
- the yoke layer 79 covering the upper write wiring 75 of the 72 is magnetically coupled to effectively reduce the bias magnetic field applied to the magnetoresistive element.
- the magnetic film 77 guides the bias magnetic field generated by the yoke layer 78 covering the upper write wiring 73 to the yoke layer 79 covering the upper write wiring 75, or the yoke layer covering the upper write wiring 75.
- the bias magnetic field generated by 79 is guided to the yoke layer 78 covering the upper write wiring 73. Due to the action of the magnetic film 77, the magnetic field generated by the magnetic poles generated at the ends of the yoke layers 78 and 79 facing the magnetic film 77 does not link with the magnetoresistive element. Therefore, the magnetic film 77 effectively reduces the bias magnetic field linked to the magnetoresistive element.
- the upper write wires 73, 75 having a length of 100 ⁇ m, a width of 1 ⁇ m, and a thickness of 0.3 ⁇ m are covered with yoke layers 78, 79 having a thickness of 50 nm.
- the magnetic film 77 is made of NiFe having a thickness of 50 ⁇ m and is separated from the upper write wirings 73 and 75 by an insulating film 80 having a thickness of 20 nm.
- the end force of the upper write wiring 73 (or the upper write wiring 75) on the side of the magnetic film 77 substantially links the emitted magnetic field to the magnetic film 77, and the magnetoresistive element of the magnetic field No leakage is found.
- an insulating magnetic film 77 is used instead of the conductive magnetic film 77. 'Can be formed.
- the insulating magnetic film 77 ′ can be formed directly in contact with the yoke layers 78, 79.
- the direct contact of the insulating magnetic film 77 ′ with the yoke layers 78, 79 enhances the magnetic coupling between the insulating magnetic film 77 ′ and the yoke layers 78, 79.
- upper write wiring 73 of block 71 and upper write wiring 75 of block 72 are sufficiently provided. It can be located nearby. By sufficiently bringing the upper write wiring 73 and the upper write wiring 75 close to each other, a magnetic field generated by the yoke layer 78 covering the upper write wiring 73 is guided to the yoke layer 79 covering the upper write wiring 75, or The magnetic field generated by the yoke layer 79 covering the write wiring 75 is guided to the yoke layer 78 covering the upper write wiring 73.
- the structure of FIG. 33 like the structure shown in FIG. 30, effectively reduces the bias magnetic field applied to the magnetoresistive element.
- FIG. 34 shows a sixth embodiment of the MRAM according to the present invention.
- An upper write wiring 81 whose side and upper surface are covered by a yoke layer extends in the X-axis direction
- a lower write wiring 82 whose side and lower surface are covered by the yoke layer extends in the y-axis direction.
- a magnetoresistive element 83 is provided at each position where the upper write wiring 81 and the lower write wiring 82 intersect.
- the ends 81a and 82a of the yoke layer covering the upper write wiring 81 and the lower write wiring 82 affect the characteristics of the magnetoresistive element. It is located far enough that it cannot be reached. When the ends 81a and 82a of the yoke layer are sufficiently far away from the magnetoresistive element, the distance from the magnetic pole generated at the end of the yoke layer to the magnetic resistance element is sufficiently increased.
- the distance from the ends 81a and 82a of the yoke layer to the magnetoresistive element should be sufficiently large to increase the distance from the end of the yoke layer.
- the component linked to the magnetoresistive element can be made sufficiently small. Thereby, the bias magnetic field applied to the magnetoresistive element can be reduced to such an extent that the characteristics of the magnetoresistive element are not affected.
- the end 81a of the yoke layer covering the upper write wiring 81 is generated at the end 81a.
- the intrinsic coercive magnetic field of the free ferromagnetic layer of the magnetoresistive element 83 is defined as when a magnetic field is applied to the free ferromagnetic layer in a direction perpendicular to its magnetization. Means coercive field.
- the end 82a of the yoke layer covering the lower write wiring 82 has a magnitude of a bias magnetic field that causes a magnetic pole generated at the end 82a to interlink with the magnetoresistive element 83 closest to the end 82a. Separated from the closest magnetoresistive element 83 so as to be less than one-fifth, more preferably less than one-tenth, of the intrinsic coercive field of the free ferromagnetic layer. Force is suitable.
- the end 81a of the yoke layer that covers the upper write wiring 81 is preferably at least the minimum pitch between the lower write wiring 82 and the distance from the closest magnetoresistive element 83, and more preferably the minimum pitch. It is preferable to be separated from the closest magnetoresistive element 83 so as to be three times or more the pitch.
- the minimum pitch of the lower write wiring 82 means the minimum pitch dx of the center line of the lower write wiring 82.
- the end 82a of the yoke layer covering the lower write wiring 82 is preferably at least the minimum pitch of the upper write wiring 81, more preferably the distance from the closest magnetoresistive element 83. It is preferable to be separated from the closest magnetoresistive element 83 so as to be three times or more of the above.
- the minimum pitch of the upper write wiring 81 means the minimum distance dy of the center line distance dy of the upper write wiring 81.
- the bias magnetic field linked to the magnetoresistive element 83 is reduced.
- the upper write wiring 81 having a length of 100 ⁇ m, a width of 1 ⁇ m, and a thickness of 0.3 ⁇ m is made of Ni having a thickness of 50 nm.
- the yoke layer is formed by Fe.
- the x-axis component of the magnetic field at a position 10 / im away from the end of the overwrite wiring 81 in the X-axis direction and 0.1 / im away from the lower surface of the upper write wiring 81 is about 10 ( ⁇ e). is there.
- the component of the magnetic field in the X-axis direction at a position 20 zm away from the end of the upper write wiring 81 in the X-axis direction and 0.1 ⁇ m away from the lower surface of the upper write wiring 81 is about 3 (Oe).
- the bias magnetic field applied to the magnetoresistive element can be reduced to about one third.
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Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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US10/561,213 US7477538B2 (en) | 2003-06-20 | 2004-06-16 | Magnetic random access memory |
JP2005507221A JP4835974B2 (ja) | 2003-06-20 | 2004-06-16 | 磁気ランダムアクセスメモリ |
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JP2003-176699 | 2003-06-20 | ||
JP2003176699 | 2003-06-20 |
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WO2006035943A1 (ja) * | 2004-09-30 | 2006-04-06 | Tdk Corporation | 磁気メモリ |
JP5163638B2 (ja) * | 2007-03-07 | 2013-03-13 | 日本電気株式会社 | 磁性体装置及び磁気記憶装置 |
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US7545662B2 (en) * | 2005-03-25 | 2009-06-09 | Taiwan Semiconductor Manufacturing Co., Ltd. | Method and system for magnetic shielding in semiconductor integrated circuit |
US9024581B2 (en) * | 2008-05-21 | 2015-05-05 | James W. McGinley | Charger plug with improved package |
WO2010146863A1 (ja) * | 2009-06-17 | 2010-12-23 | 日本電気株式会社 | Icパッケージ |
US10553783B2 (en) | 2018-06-29 | 2020-02-04 | Sandisk Technologies Llc | Spin orbit torque magnetoresistive random access memory containing shielding element and method of making thereof |
US10381551B1 (en) * | 2018-06-29 | 2019-08-13 | Sandisk Technologies Llc | Spin orbit torque magnetoresistive random access memory containing shielding element and method of making thereof |
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JP5163638B2 (ja) * | 2007-03-07 | 2013-03-13 | 日本電気株式会社 | 磁性体装置及び磁気記憶装置 |
Also Published As
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US20060132987A1 (en) | 2006-06-22 |
JP4835974B2 (ja) | 2011-12-14 |
JPWO2004114409A1 (ja) | 2006-08-03 |
US7477538B2 (en) | 2009-01-13 |
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